CN110829561A - Lithium battery charging current limiting circuit following input power - Google Patents
Lithium battery charging current limiting circuit following input power Download PDFInfo
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- CN110829561A CN110829561A CN201911152196.5A CN201911152196A CN110829561A CN 110829561 A CN110829561 A CN 110829561A CN 201911152196 A CN201911152196 A CN 201911152196A CN 110829561 A CN110829561 A CN 110829561A
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- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 50
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 50
- 238000001514 detection method Methods 0.000 claims abstract description 17
- 238000001914 filtration Methods 0.000 claims abstract description 5
- 230000003321 amplification Effects 0.000 claims abstract description 4
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 4
- 239000003990 capacitor Substances 0.000 claims description 13
- 238000012423 maintenance Methods 0.000 claims description 5
- 238000003745 diagnosis Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
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Abstract
The invention discloses a lithium battery charging current limiting circuit following input power, which comprises an input power detection circuit, a comparator circuit, a reference generation circuit and a following protection circuit, wherein the input power detection circuit acquires primary working current and obtains a direct current signal with a determined voltage change range after rectification and filtering processing, the comparator circuit compares the voltage of the direct current signal with 3 threshold voltages to generate 3 control signals, the reference generation circuit generates different reference voltages according to the 3 control signals, and the following protection circuit generates a current reference signal of a lithium battery charging circuit through following amplification according to the reference voltage. The invention realizes the function of instantly, flexibly and variably changing the charging current of the lithium battery equipped by the device under different energy taking power conditions through a simple hardware circuit, has simple circuit structure, lower requirements on the parameters of components, stable and reliable circuit operation, low misjudgment rate of the device and quick and real-time current response.
Description
Technical Field
The present invention relates to a current limiting circuit, and more particularly, to a current limiting circuit for lithium battery charging that follows input power.
Background
At present, self-energy-taking devices are widely applied, such as fault diagnosis devices installed outdoors and the like, and are characterized in that power supply power is influenced by primary current, the power is limited and is easy to fluctuate. These self-powered devices require a lithium battery due to the requirements of the operating environment. Because the self-energy-taking power supply mode is adopted, the primary side current directly determines the power supply power of the device. Under the condition of a weak-power working condition, the reliable work of the device is ensured, meanwhile, the lithium battery pack is required to be charged and maintained frequently, and the lithium battery is ensured to be in a full-charge state. Because the power supply power of the device adopts a self-energy-obtaining design scheme, the power of the device is directly influenced by primary current. In order to ensure that the lithium battery is timely and effectively maintained and ensure that the device can reliably work with sufficient power, a simple and reliable technical solution is designed for the current limiting of the lithium battery charging control circuit.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to solve the technical problem of providing a lithium battery charging current limiting circuit following input power, which determines the charging current of a lithium battery according to the magnitude of energy taking current, realizes flexible real-time adjustment of the charging current under different energy taking power conditions, and avoids system reset caused by insufficient energy taking power.
The technical scheme is as follows: the lithium battery charging current limiting circuit following the input power comprises an input power detection circuit 11, a comparator circuit 12, a reference generation circuit 13 and a following protection circuit 14,
the input power detection circuit 11 obtains a primary working current, and obtains a direct current signal with a determined voltage change range after rectification and filtering processing;
the comparator circuit 12 compares the voltage of the direct current signal with 3 threshold voltages to generate 3 paths of control signals;
the reference generating circuit 13 generates different reference voltages according to the 3 paths of control signals;
the following protection circuit 14 generates a current reference signal of the lithium battery charging circuit through following amplification according to the reference voltage.
Further, the input power detection circuit 11 includes an energy-taking transformer, the energy-taking transformer monitors a primary working current, the energy-taking transformer is connected with a diode D1, a diode D1 is connected with a capacitor C1 and a resistor R1, the resistor R1 is connected with a resistor R2, a resistor R2 is grounded, and a resistor R1 is connected with a voltage V-at an end of the resistor R2 and is input into the comparator circuit 12.
Further, the comparator circuit 12 includes comparators U1A, and U1A, negative input terminals of the comparators U1A, and U1A are connected to the output terminal of the input power detection circuit 11, a positive input terminal of the comparator U1A is connected to resistors R A and R A, the resistor R A is connected to VCC voltage, the resistor R A is grounded, an output terminal of the comparator U1A is connected to the resistor R A, the resistor R A is connected to a pull-down resistor R A, a positive input terminal of the comparator U1A is connected to the resistors R A and R A, the resistor R A is connected to VCC voltage, the resistor R A is grounded, an output terminal of the comparator U1A is connected to the resistor R A, the positive input terminal of the comparator U1A is connected to the resistors R A and R A, the resistor R A is connected to the resistor R A, the resistor R A is connected to ground, the output terminal of the comparator U1A is connected to the resistor R A, and the resistor R A is connected to the pull-down resistor R A.
Further, 3 transistors are provided in the reference generating circuit 13, and different reference voltages are generated according to the combination of conduction and closing of the transistors.
Further, the reference generating circuit 13 includes transistors Q1, Q2, Q3, the 3 control signals are respectively connected to bases of transistors Q1, Q2, Q3, emitters of transistors Q1, Q2, Q3 are grounded, a collector of transistor Q1 is connected to a resistor R16, a collector of transistor Q2 is connected to a resistor R17, a collector of transistor Q3 is connected to a resistor R18, one end of the resistor R15 is connected to the VCC voltage, and the other end is connected to resistors R16, R17, R18 and a pull-down resistor R19, and outputs the reference voltage Iref.
Further, the follow protection circuit 14 includes an operational amplifier U2, a positive input terminal of the operational amplifier U2 is connected to the output terminal of the reference generation circuit 13, the filter capacitor C2, and the anode of the diode D2, the other terminal of the filter capacitor C2 and the cathode of the diode D2 are grounded, a negative input terminal of the operational amplifier U2 is connected to the resistor R20, and an output terminal of the operational amplifier U2 is connected to the resistor R20 and serves as a current reference signal of the lithium battery charging circuit.
Further, the system also comprises a CPU, wherein the CPU is connected with the input power detection circuit 11 and the lithium battery charging circuit, and the CPU determines whether the lithium battery needs to be charged and maintained or not according to the current energy taking power and the capacity condition of the lithium battery.
Further, the CPU monitors the energy taking power, when the energy taking power reaches a set value, a battery maintenance instruction is sent to charge the battery, and when the voltage of the lithium battery reaches 8.4V or the charging current is smaller than 10mA, a charging stopping instruction is sent.
Has the advantages that: the invention realizes the function of instantly and flexibly changing the charging current of the lithium battery equipped by the device under different energy taking power conditions through a simpler hardware circuit, has simple circuit structure, lower requirements on the parameters of components, low cost, stable and reliable circuit operation and low misjudgment rate of the device, judges the charging current according to the energy taking power, does not depend on CPU operation processing, and has quick and real-time current response.
Drawings
Fig. 1 is a module connection diagram of the present embodiment;
fig. 2 is a circuit diagram of an input power detection circuit and a comparator circuit in the present embodiment;
fig. 3 is a circuit diagram of a reference generation circuit and a follow-up protection circuit in the present embodiment.
Detailed Description
As shown in fig. 1, the lithium battery charging current limiting circuit according to the present embodiment includes an input power detection circuit 11, a comparator circuit 12, a reference generation circuit 13, and a follow protection circuit 14. The embodiment is used for a self-powered fault diagnosis device which obtains electric energy through a primary cable. The input power detection circuit 11 monitors the primary cable working current through an energy-taking mutual inductor (CT), and rectifies and filters the current to obtain a direct current signal with a voltage change range that can be determined, and the comparator circuit 12 compares the voltage of the direct current signal with 3 threshold voltages to generate 3 paths of control signals. The 3 paths of control signals respectively control 3 triodes in the reference generating circuit 13, different reference voltages are generated through the combination of conduction and closing of the triodes, the reference voltages pass through the following protection circuit 14, are subjected to following amplification, and then serve as current given reference signals for the lithium battery charging circuit.
The circuit connections in this embodiment are shown in fig. 2 and 3. The input power detection circuit 11 comprises an energy-taking transformer, the energy-taking transformer monitors primary working current, the energy-taking transformer is connected with a diode D1, a diode D1 is connected with a capacitor C1 and a resistor R1, the resistor R1 is connected with a resistor R2, a resistor R2 is grounded, and a resistor R1 is connected with a voltage V-at the end of the resistor R2 and is input into the comparator circuit 12. The comparator circuit 12 comprises comparators U1A, U1B and U1C, negative input terminals of comparators U1A, U1B and U1C are connected with V-, a positive input terminal of comparator U1A is connected with resistors R3 and R4, a threshold voltage Vref1 is a positive input terminal of comparator U1A, a resistor R3 is connected with VCC voltage, a resistor R4 is grounded, an output terminal of comparator U1A is connected with a resistor R9, the other terminal of resistor R9 is an output signal OUT1 and is connected with a pull-down resistor R10, a positive input terminal of comparator U1B is connected with resistors R5 and R6, a threshold voltage Vref2 is a positive input terminal of comparator U1B, a resistor R5 is connected with VCC voltage, a resistor R6 is grounded, an output terminal of comparator U1B is connected with a resistor R B, the other terminal of resistor R B is an output signal OUT B and is connected with a pull-down resistor R B, positive input terminal of the comparator U1R B and the resistor Vref B is connected with the positive input terminal of the resistor Vref B and the resistor R B and the positive input terminal of the comparator U1B, the output end of the comparator U1C is connected with a resistor R13, the other end of the resistor R13 is an output signal OUT3, and the other end of the resistor R13 is connected with a pull-down resistor R14. Wherein Vref1> Vref2> Vref 3. The reference generating circuit 13 includes transistors Q1, Q2, Q3, the 3 control signals OUT1, OUT2, OUT3 are connected to the bases of transistors Q1, Q2, Q3, the emitters of transistors Q1, Q2, Q3 are grounded, the collector of transistor Q1 is connected to a resistor R16, the collector of transistor Q2 is connected to a resistor R17, the collector of transistor Q3 is connected to a resistor R18, one end of the resistor R15 is connected to VCC voltage, the other end is connected to resistors R16, R17, R18 and a pull-down resistor R19, and outputs the reference voltage Iref. The follow protection circuit 14 comprises an operational amplifier U2, wherein the positive input end of the operational amplifier U2 is connected with the output end Iref of the reference generation circuit 13, the filter capacitor C2 and the positive electrode of a diode D2, the other end of the filter capacitor C2 and the negative electrode of a diode D2 are grounded, the negative input end of the operational amplifier U2 is connected with a resistor R20, and the output end of the operational amplifier U2 is connected with R20 and used as a current reference signal of the lithium battery charging circuit.
Preferably, the system further comprises a CPU, the CPU is connected to the input power detection circuit 11 and the lithium battery charging circuit, and the CPU determines whether to perform charging maintenance on the lithium battery according to the current energy-taking power, the current capacity state of the lithium battery, the current environmental temperature and other conditions.
The working principle of the circuit is that when the connected fault diagnosis device works normally, the fault diagnosis device obtains electric energy through one-time cable energy taking. The energy-taking mutual inductor (CT) monitors the working current of the primary cable, and rectifies an alternating current signal through a diode D1 and forms a direct current signal after filtering through a capacitor C1. In order to ensure the filtering effect of the capacitor, the resistors R1 and R2 are generally selected to have larger resistance values, and the voltage V-obtained by dividing the voltage of the capacitor enters the negative input ends of the comparators U1A, U1B and U1C. The charging current of the lithium battery needs to follow the magnitude of the energy taking power, in order to judge the condition of the energy taking power, threshold voltages Vref1, Vref2 and Vref3 are connected to the positive input ends of comparators U1A, U1B and U1C, the threshold voltages are obtained by VCC through voltage dividing resistors, a high-precision reference voltage source is not needed, and Vref1> Vref2> Vref3 are provided. The output of the comparator circuit 12 is specifically described as follows:
when no energy taking power exists, V is equal to 0, Out1 is equal to 1, Out2 is equal to 1, and Out3 is equal to 1;
when the energy-taking power is very low, V- < Vref3, Out1 equals 1, Out2 equals 1, and Out3 equals 1;
when the energy taking power is high, Vref3< V- < Vref2, Out1 is 0, Out2 is 1, and Out3 is 1;
when the energy-taking power is higher, Vref2< V- < Vref1, Out1 is 0, Out2 is 0, and Out3 is 1;
when the energy-taking power is very sufficient, Vref1< V-, Out1 equals 0, Out2 equals 0, and Out3 equals 0.
The output terminals of the comparators U1A, U1B and U1C pass through pull-down resistors R10, R12 and R14 respectively to avoid uncertainty of the output signals Out1, Out2 and Out 3. Out1, Out2 and Out3 respectively control the on and off of the triodes Q1, Q2 and Q3, and determine whether R16, R17 and R18 are connected with R19 in parallel, so as to generate different Iref voltage outputs. When Out1 is equal to 1, Out2 is equal to 1, and Out3 is equal to 1, Q1, Q2 and Q3 are conducted, R16, R17, R18 and R19 resistors form a parallel relation, and are connected with R15 in series, and the obtained voltage division value of Iref is very low. Iref is amplified by the filter capacitor C2 and the operational amplifier U2 to serve as a current reference signal of the lithium battery charging circuit. The outputs of Out and the rest of the combinations are analogized in turn. When the energy-taking power is sufficient, the Out output is 0, Q1, Q2 and Q3 are all closed, at the moment, Iref is obtained through voltage division of R15 and R19, the amplitude is maximum, the Iref is used as a current reference to supply the charging circuit, and at the moment, the lithium battery is rapidly charged according to the maximum charging current.
The embodiment is applied to an outdoor fault diagnosis device for self-powered electricity, the current energy-taking power is determined by detecting the working current at the primary side, and the system CPU determines whether to charge and maintain the lithium battery according to the current battery condition, the current device energy-taking power condition, the environmental condition and other factors. In the charging process, the circuit monitors the energy taking current of the current device in real time, uninterruptedly and instantaneously adjusts the charging current of the lithium battery, and the normal working power of the device is also ensured while the charging of the battery is ensured as much as possible, so that the device can normally operate. During the charging process, when the charging is completed or the condition for continuing the charging cannot be satisfied because of other reasons such as the ambient temperature, the device CPU issues a related control function for stopping the charging. For the lithium battery, under the condition that the energy taking power is normal, the CPU sends a battery maintenance instruction to charge the battery, and when the battery voltage reaches 8.4V and the charging current is less than 10mA, the CPU sends a charging stopping instruction, and the system finishes the lithium battery charging maintenance work. In the charging process, the device detects the current energy taking power of the device in real time, and determines the current charging current according to the energy taking power: when the energy taking current is lower than 15A, the charging current is 0 mA; when the energy taking current is not more than 20A, the charging current is 50 mA; when the energy taking current is 20-30A, the charging current is 100 mA; in other cases, the maximum charging current of the lithium battery is 300 mA.
Claims (8)
1. A lithium battery charging current limiting circuit that follows an input power, characterized by: comprises an input power detection circuit 11, a comparator circuit 12, a reference generation circuit 13 and a follow protection circuit 14,
the input power detection circuit 11 obtains a primary working current, and obtains a direct current signal with a determined voltage change range after rectification and filtering processing;
the comparator circuit 12 compares the voltage of the direct current signal with 3 threshold voltages to generate 3 paths of control signals;
the reference generating circuit 13 generates different reference voltages according to the 3 paths of control signals;
the following protection circuit 14 generates a current reference signal of the lithium battery charging circuit through following amplification according to the reference voltage.
2. The input power following lithium battery charging current limiting circuit of claim 1, wherein: the input power detection circuit 11 comprises an energy-taking transformer, the energy-taking transformer monitors primary working current, the energy-taking transformer is connected with the anode of a diode D1, the cathode of the diode D1 is connected with a capacitor C1 and a resistor R1, the resistor R1 is connected with a resistor R2, a resistor R2 is grounded, and the resistor R1 is connected with the voltage V-at the end of the resistor R2 and is input into the comparator circuit 12.
3. The input power following lithium battery charging current limiting circuit of claim 1, wherein: the comparator circuit 12 includes comparators U1A, negative input terminals of the comparators U1A, U1A are connected to the output terminal of the input power detection circuit 11, a positive input terminal of the comparator U1A is connected to resistors R A, the resistor R A is connected to VCC voltage, the resistor R A is grounded, an output terminal of the comparator U1A is connected to the resistor R A, the resistor R A is connected to a pull-down resistor R A, a positive input terminal of the comparator U1A is connected to the resistors R A, R A is connected to VCC voltage, the resistor R A is grounded, an output terminal of the comparator U1A is connected to the resistor R A, the resistor R A is connected to the pull-down resistor R A, the positive input terminal of the comparator U1A is connected to the resistors R A, R A is connected to the pull-down resistor R A, the resistor R A is connected to the VCC voltage, the output terminal of the comparator U1A is connected to the resistor R A, and the resistor R A is connected to the.
4. The input power following lithium battery charging current limiting circuit of claim 1, wherein: the reference generating circuit 13 is provided with 3 transistors, and generates different reference voltages according to the combination of conduction and closing of the transistors.
5. The input power following lithium battery charging current limiting circuit of claim 4, wherein: the reference generating circuit 13 includes triodes Q1, Q2, Q3, the 3 control signals are respectively connected to bases of triodes Q1, Q2, Q3, emitters of triodes Q1, Q2, Q3 are grounded, a collector of the triode Q1 is connected with a resistor R16, a collector of the triode Q2 is connected with a resistor R17, a collector of the triode Q3 is connected with a resistor R18, one end of the resistor R15 is connected with VCC voltage, and the other end is connected with resistors R16, R17, R18 and a pull-down resistor R19, and outputs a reference voltage Iref.
6. The input power following lithium battery charging current limiting circuit of claim 1, wherein: the follow protection circuit 14 comprises an operational amplifier U2, wherein the positive input end of the operational amplifier U2 is connected with the output end of the reference generation circuit 13, the filter capacitor C2 and the positive electrode of a diode D2, the other end of the filter capacitor C2 and the negative electrode of a diode D2 are grounded, the negative input end of the operational amplifier U2 is connected with a resistor R20, and the output end of the operational amplifier U2 is connected with R20 and used as a current reference signal of the lithium battery charging circuit.
7. The input power following lithium battery charging current limiting circuit of claim 1, wherein: the lithium battery charging system further comprises a CPU, the CPU is connected with the input power detection circuit 11 and the lithium battery charging circuit, and the CPU determines whether the lithium battery needs to be charged and maintained or not according to the current energy-taking power and the capacity condition of the lithium battery.
8. The input power following lithium battery charging current limiting circuit of claim 1, wherein: the CPU monitors the energy taking power, when the energy taking power reaches a set value, a battery maintenance instruction is sent to charge the battery, and when the voltage of the lithium battery reaches 8.4V or the charging current is less than 10mA, a charging stopping instruction is sent.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911152196.5A CN110829561A (en) | 2019-11-22 | 2019-11-22 | Lithium battery charging current limiting circuit following input power |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911152196.5A CN110829561A (en) | 2019-11-22 | 2019-11-22 | Lithium battery charging current limiting circuit following input power |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101888121A (en) * | 2010-06-09 | 2010-11-17 | 重庆大学 | Energy acquisition and power supply management device of current transformer of overhead line |
| CN210577916U (en) * | 2019-11-22 | 2020-05-19 | 香江科技股份有限公司 | Lithium battery charging current limiting circuit following input power |
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2019
- 2019-11-22 CN CN201911152196.5A patent/CN110829561A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101888121A (en) * | 2010-06-09 | 2010-11-17 | 重庆大学 | Energy acquisition and power supply management device of current transformer of overhead line |
| CN210577916U (en) * | 2019-11-22 | 2020-05-19 | 香江科技股份有限公司 | Lithium battery charging current limiting circuit following input power |
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Country or region after: China Address after: No. 666, Chunliu North Road, Yangzhong City, Zhenjiang City, Jiangsu Province, 212299 Applicant after: Xiangjiang Technology (Group) Co.,Ltd. Applicant after: ZHENJIANG XIANGJIANGYUN POWER TECHNOLOGY Co.,Ltd. Address before: No. 666, Chunliu North Road, Yangzhong City, Zhenjiang City, Jiangsu Province, 212299 Applicant before: XIANGJIANG TECHNOLOGY Co.,Ltd. Country or region before: China Applicant before: ZHENJIANG XIANGJIANGYUN POWER TECHNOLOGY Co.,Ltd. |
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